Re: [PATCH 2/2] PCI: Don't fail BAR resize if nothing is reassigned

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Am 15.12.21 um 15:16 schrieb Michał Winiarski:
When pci_reassign_bridge_resources returns -ENOENT, it means that no
resources needed to be "moved". This can happen when the resource was
resized to be smaller, and it's completely fine - there's no need to treat
this as an error and go back to the original BAR size.

Well that doesn't make much sense as far as I can see.

Drivers mandatory need to call pci_release_resource() on all resources which might need to move for a resize, including the one which is about to be resized.

When you get -ENOENT from pci_reassign_bridge_resources() it just means that the function was not able to do it's work because the driver failed to release it's resources before the resize.

Technically we could indeed skip this step if the new size is smaller than the old size, but then the question is why would somebody resize in the first place? The freed up address space is not usable if you don't do this.

Regards,
Christian.


Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx>
---
  drivers/pci/setup-res.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 1946e52e7678a..5de5129055e0a 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -484,7 +484,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
  	/* Check if the new config works by trying to assign everything. */
  	if (dev->bus->self) {
  		ret = pci_reassign_bridge_resources(dev->bus->self, res->flags);
-		if (ret)
+		if (ret && ret != -ENOENT)
  			goto error_resize;
  	}
  	return 0;




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